From b77e4e915b7dcc91bf875229c39a79db04e09908 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Wed, 22 Sep 2021 20:26:40 -0700
Subject: [PATCH] Add some clarity on the license/license-file warning.

---
 src/cargo/util/toml/mod.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/cargo/util/toml/mod.rs b/src/cargo/util/toml/mod.rs
index c4d19de3afa..cdf84c6dc8e 100644
--- a/src/cargo/util/toml/mod.rs
+++ b/src/cargo/util/toml/mod.rs
@@ -1398,8 +1398,12 @@ impl TomlManifest {
         );
         if project.license_file.is_some() && project.license.is_some() {
             manifest.warnings_mut().add_warning(
-                "only one of `license` or \
-                 `license-file` is necessary"
+                "only one of `license` or `license-file` is necessary\n\
+                 `license` should be used if the package license can be expressed \
+                 with a standard SPDX expression.\n\
+                 `license-file` should be used if the package uses a non-standard license.\n\
+                 See https://doc.rust-lang.org/cargo/reference/manifest.html#the-license-and-license-file-fields \
+                 for more information."
                     .to_string(),
             );
         }